<template>
	<view class="satri-waterfall" v-if="visible">
		<!-- 纵向 -->
		<template v-if="direction === 'vertical'">
			<view class="satri-waterfall__item" v-for="(item, index) in list" :key="index">
				<slot :item="item" :index="index"></slot>
			</view>
		</template>

		<!-- 横向 -->
		<template v-else-if="direction === 'horizontal'">
			<slot :list="list"></slot>
		</template>

		<!-- 空态 -->
		<slot name="empty" v-if="showEmpty">
			<satri-empty />
		</slot>
	</view>
</template>

<script lang="ts">
import { type PropType, computed, defineComponent, ref, nextTick, getCurrentInstance } from "vue";
import { flatMap, isEmpty } from "lodash-es";
import { parseRpx } from "/@/satri/utils";
import { onShow } from "@dcloudio/uni-app";

export default defineComponent({
	name: "satri-waterfall",

	props: {
		// 列的数量
		column: {
			type: Number,
			default: 2,
		},
		// 列间隔
		gutter: {
			type: Number,
			default: 20,
		},
		// 布局方向
		direction: {
			type: String as PropType<"horizontal" | "vertical">,
			default: "horizontal",
		},
		// 匹配值
		nodeKey: {
			type: String,
			default: "id",
		},
	},

	setup(props) {
		const { proxy }: any = getCurrentInstance();

		const visible = ref(true);

		// 列表
		const list = ref<any[]>([]);

		// 每次追加的数据
		let data: any[] = [];

		// 列数量
		const columnCount = computed(() => (props.direction == "vertical" ? props.column : "none"));

		// 列间距
		const columnGap = computed(() =>
			props.direction == "vertical" ? parseRpx(props.gutter) : "none",
		);

		// 是否空
		const showEmpty = computed(() => {
			return list.value.filter((e) => !isEmpty(e)).length == 0;
		});

		// 刷新列表
		function refresh(data: any[]) {
			visible.value = false;

			nextTick(() => {
				visible.value = true;

				switch (props.direction) {
					case "horizontal":
						list.value = new Array(props.column).fill(1).map(() => []);

						// 等待 <satri-waterfall-column 渲染完成后追加数据
						nextTick(() => {
							append(data);
						});
						break;
					case "vertical":
						list.value = data;
						break;
				}
			});
		}

		// 计算高度，一个个往列表追加
		async function append(arr: any[]) {
			data = arr;

			for (let i = 0; i < arr.length; i++) {
				const next = async () => {
					const rects = await getRect();

					// 获取不到的时候阻断掉
					if (isEmpty(rects) && i !== 0) {
						return false;
					}

					// 获取 <satri-waterfall-column 的高度，比较后在最小的列中塞入
					return Promise.all(rects).then((res) => {
						let colsHeight = res.map((e) => e.height);

						let minH = Math.min(...colsHeight);
						let index = colsHeight.indexOf(minH);

						if (index < 0) {
							index = 0;
						}

						list.value[index]?.push(arr[i]);

						return true;
					});
				};

				await next();
			}
		}

		// 更新单条数据，根据nodeKey来匹配
		function update(id: string | number, data: any) {
			const next = (e: any) => {
				const d = e[props.nodeKey] === id;

				if (d) {
					Object.assign(e, data);
				}

				return Boolean(d);
			};

			switch (props.direction) {
				case "horizontal":
					list.value.find((col) => {
						return col.find(next);
					});
					break;
				case "vertical":
					list.value.find(next);
					break;
			}
		}

		// 清空列表
		function clear() {
			list.value = [];
		}

		// 获取列
		function getRect(): Promise<any> {
			return new Promise((resolve) => {
				// #ifdef MP
				let timer: any = null;

				function fn() {
					const children: any[] = proxy.$children;

					if (isEmpty(children)) {
						timer = setTimeout(() => {
							fn();
						}, 50);
					} else {
						clearTimeout(timer);
						const arr = children.filter((e) => e.getRect).map((e) => e.getRect());
						resolve(arr);
					}
				}

				fn();
				// #endif

				// #ifndef MP
				nextTick(() => {
					uni.createSelectorQuery()
						.in(proxy.$root)
						.selectAll(`.satri-waterfall-column`)
						.boundingClientRect(resolve)
						.exec();
				});
				// #endif
			});
		}

		// 重新布局，在加载中切换页面导致计算错误，返回页面时 onShow 重新计算
		function doLayout() {
			// 列空的时候 重新追加数据
			if (isEmpty(flatMap(list.value)) && !isEmpty(data)) {
				append(data);
			}
		}

		onShow(() => {
			doLayout();
		});

		return {
			visible,
			list,
			columnCount,
			columnGap,
			refresh,
			append,
			update,
			clear,
			showEmpty,
			doLayout,
		};
	},
});
</script>
